Angiotensin converting enzyme inhibitors may have beneficial effects over other antihypertensive agents in progressive renal disease of various origins including diabetic nephropathy, essential hypertension and other intrinsic renal diseases (See, e.g., Hypertension: Pathophysiology, Diagnosis, and Management, ed. by J. H. Laragh and B. M. Brenner, vol. 1, pp. 1163-1176, Raven Press, Ltd., New York, 1990; Hypertension: Pathophysiology, Diagnosis, and Management, ed. by J. H. Laragh and B. M. Brenner, vol. 2, pp. 1677-1687, Raven Press, Ltd., New York, 1990). For instance, in partially nephrectomized rats, glomerular capillary hypertension in the remnant kidney is associated with progressive proteinuria, focal glomerular sclerosis, and moderate hypertension. Angiotensin converting enzyme inhibitors, which lower systemic arterial pressure and glomerular capillary pressure, limit the progression of glomerular injury.
There are other antihypertensive agents which lower systemic arterial blood pressure to a similar extent, but fail to reduce glomerular capillary pressure. Such agents do not prevent the progression of glomerular injury. It is speculated that in these rats intrarenal generation of angiotensin-II constricts the renal efferent arteriole and causes an increase in glomerular hydraulic pressure. Glomerular hyperfiltration, hyperperfusion and/or hypertension may then initiate and induce glomerular lesions. Thus, blockade of the intrarenal formation of angiotensin-II by angiotensin converting enzyme inhibitors may retard the deterioration of renal failure.
Although the partially nephrectomized rat is associated with moderate hypertension, systemic hypertension does not appear to be necessary for the acceleration of renal disease. In the insulin-treated rat with streptozocin-induced diabetes, systemic arterial pressure is normal but glomerular capillary pressure is high. Similar to the partially nephrectomized rat model, angiotensin converting enzyme inhibitors are beneficial in limiting the glomerular structural lesions, suggesting that glomerular capillary hypertension but not systemic arterial hypertension play a critical role in rats with progressive renal failure.
Nonpeptide angiotensin-II receptor antagonists are believed to be more efficacious than angiotensin converting enzyme inhibitors in treating chronic renal failure because the nonpeptide angiotensin-II receptor antagonists may block the renal effect of angiotensin-II more completely irrespective of the source of angiotensin-II. In contrast, angiotensin converting enzyme inhibitors selectively block kininase II and, thus, may not inhibit totally the local formation of angiotensin-II in the kidney. Other types of peptidyl dipeptidase may also be responsible for the formation of angiotensin-II. (Wong, P. C. and Zimmerman, B. G.: Role of Extrarenal and Intrarenal Converting Enzyme Inhibition in Renal Vasodilator Response to Intravenous Captopril. Life Sci. 27: 1291, 1980; Schmidt M., Giesen-Crouse, E. M., Krieger, J. P., Welsch, C. and Imbs, J. L.: Effect of angiotensin converting enzyme inhibitors on the vasoconstrictor action of angiotensin I on isolated rat kidney. J. Cardiovasc. Pharmacol. 8 (Suppl. 10): S100, 1986)).
In clinical renal artery stenosis, the usefulness of angiotensin converting enzyme inhibitors may be limited by a reversible loss of filtration in the stenotic kidney. It is possible that nonpeptide angiotensin II receptor antagonists may have a similar renal effect in the stenotic kidney.
K. Matsumura, et al., in U.S. Pat. No. 4,207,324 issued Jun. 10, 1980 discloses 1,2-disubstituted-4-haloimidazole-5-acetic acid derivatives of the formula: ##STR1## wherein R.sup.1 is hydrogen, nitro or amino; R.sup.2 is phenyl, furyl or thienyl optionally substituted by halogen, lower alkyl, lower alkoxy or di-lower alkylamino; R.sup.3 is hydrogen or lower alkyl and X is halogen; and their physiologically acceptable salts. These compounds have diuretic and hypotensive actions.
Furukawa, et al., in U.S. Pat. No. 4,355,040 issued Oct. 19, 1982 discloses hypotensive imidazole-5-acetic acid derivatives having the formula: ##STR2## wherein R.sup.1 is lower alkyl, cycloalkyl, or phenyl optionally substituted; X.sup.1, X.sup.2, and X.sup.3 are each hydrogen, halogen, nitro, amino, lower alkyl, lower alkoxy, benzyloxy, or hydroxy; Y is halogen and R.sup.2 is hydrogen or lower alkyl; and salts thereof.
Furukawa, et al., in U.S. Pat. No. 4,340,598, issued Jul. 20, 1982, discloses hypotensive imidazole derivatives of the formula: ##STR3## wherein R.sup.1 is lower alkyl or, phenyl C.sub.1-2 alkyl optionally substituted with halogen or nitro; R.sup.2 is lower alkyl, cycloalkyl or phenyl optionally substituted; one of R.sup.3 and R.sup.4 is --(CH.sub.2).sub.n COR.sup.5 where R.sup.5 is amino, lower alkoxyl or hydroxyl and n is 0, 1, 2 and the other of R.sup.3 and R.sup.4 is hydrogen or halogen; provided that R.sup.1 is lower alkyl or phenethyl when R.sup.3 is hydrogen, n=1 and R.sup.5 is lower alkoxyl or hydroxyl; and salts thereof.
Furukawa et al., in European Patent Application 103,647 discloses 4-chloro-2-phenylimidazole-5-acetic acid derivatives useful for treating edema and hypertension of the formula: ##STR4## where R represents lower alkyl and salts thereof.
The metabolism and disposition of hypotensive agent 4-chloro-1-(4-methoxy-3-methylbenzyl)-2-phenyl-imidazole-5-acetic acid is discloses by H. Torii in Takeda Kenkyushoho, 41, No 3/4, 180-191 (1982).
Frazee et al., in European Patent Application 125,033-A discloses 1-phenyl(alkyl)-2-(alkyl)-thioimidazole derivatives which are inhibitors of dopamine-.beta.-hydroxylase and are useful as antihypertensives, diuretics and cardiotonics. European Patent Application 146,228 filed Oct. 16, 1984 by S. S. L. Parhi discloses a process for the preparation of 1-substituted-5-hydroxymethyl-2-mercaptoimidazoles.
A number of references disclose 1-benzyl-imidazoles such as U.S. Pat. No. 4,448,781 to Cross and Dickinson (issued May 15, 1984); U.S. Pat. No. 4,226,878 to Ilzuka et al. (issued Oct. 7, 1980); U.S. Pat. No. 3,772,315 to Regel et al. (issued Nov. 13, 1973); U.S. Pat. No. 4,379,927 to Vorbruggen et al. (issued Apr. 12, 1983); amongst others.
Pals et al., Circulation Research, 29, 673 (1971) describe the introduction of a sarcosin residue in position 1 and alanine in position 8 of the endogenous vasoconstrictor hormone AII to yield an (octa)peptide that blocks the effects of AII on the blood pressure of pithed rats. This analog, [Sar.sup.1, Ala.sup.8 ] AII, initially called "P-113" and subsequently "Saralasin", was found to be one of the most potent competitive antagonists of the actions of AII, although, like most of the so-called peptide-AII-antagonists, it also possesses agonistic actions of its own. Saralasin has been demonstrated to lower arterial pressure in mammals and man when the (elevated) pressure is dependent on circulating AII (Pals et al., Circulation Research, 29, 673 (1971); Streeten and Anderson, Handbook of Hypertension, Vol. 5, Clinical Pharmacology of Antihypertensive Drugs, A. E. Doyle (Editor), Elsevier Science Publishers B. V., p. 246 (1984)). However, due to its agonistic character, saralasin generally elicits pressor effects when the pressure is not sustained by AII. Being a peptide, the pharmacological effects to saralasin are relatively short-lasting and are only manifest after parenteral administration, oral doses being ineffective. Although the therapeutic uses of peptide AII-blockers, like saralasin, are severely limited due to their oral ineffectiveness and short duration of action, their major utility is as a pharmaceutical standard.